Rework UnexpectedErrorPopup to be more practical

- Instead of opening a popup for every single error that occurs,
  combine them into an unique one

- Increase the maximum width, make those tracebacks readable

src/gui/PythonBridge/PythonBridge.qml

@@ -60,9 +60,8 @@ Python {
             return
         }
 
-        window.makePopup(
-            "Popups/UnexpectedErrorPopup.qml",
-            { errorType: type, message, traceback },
-        )
+        const popup = window.mainUI.unexpectedErrorPopup
+        popup.errors.unshift({type, message, traceback})
+        popup.errorsChanged()
     }
 }